Minamata disease (MD) was first recognized in May 1956. Its first recognized victims were 3 and 5 years old children. Environmental contamination most rapidly and seriously affected the physiologically and socially weak among the residents. Methylmercury (MeHg) had accumulated in fishes and shellfishes and those who ate them had been poisoning with it.MD is an indirect poisoning by MeHg through the food chain as a result of environmental contamination, and is the first known disease to cause abnormalities in the fetus due to a toxic substances passing through the placenta. In 1962 MeHg poisoning through the placenta was found for the first time in the world. It used to be considered that poisoning was caused by direct exposure to a toxic substance, and that toxic substances did not pass the placenta. MD had implications in various fields. Namely it also stirred up legal, ethical, and eugenic arguments concerning fetal protection. Also man thought about a man's worth.
